✨ 'if then else' expressions.

doc/roza.bnf

@@ -3,12 +3,15 @@ EXPR ::=
 | ASSERT
 | VARDECL
 | VARSET
-| BLOCK
+| SCOPE
+| IF
 | OR
 ASSERT ::= assert EXPR
 VARDECL ::= let ident assign EXPR
 VARSET ::= ident assign EXPR
-BLOCK ::= begin EXPR* end
+BLOCK ::= EXPR*
+SCOPE ::= begin BLOCK end
+IF ::= if EXPR then BLOCK (else BLOCK | IF)? end
 OR ::= AND (or AND)*
 AND ::= EQNE (and EQNE)*
 EQNE ::=

lib/compiler.c

@@ -309,6 +309,10 @@ int compiler_run(compiler_t* compiler, node_t* node)
         }
     } break;
 
+    case NODE_SCOPE: {
+      compiler_run(compiler, (node_t*) node->children.data[0]);
+    } break;
+
     case NODE_BLOCK: {
       compiler->scope++;
       for (size_t i=0; i<node->children.size; i++)
@@ -319,6 +323,23 @@ int compiler_run(compiler_t* compiler, node_t* node)
       compiler->scope--;
     } break;
 
+    case NODE_IF: {
+      size_t const IF_LIMIT = 1024;
+
+      int end_points[IF_LIMIT];
+      size_t size = 0;
+
+      compiler_run_if(compiler, node, end_points, &size);
+      assert(size < IF_LIMIT);
+
+      for (size_t i=0; i<size; i++)
+        {
+          compiler->mod->program.params[end_points[i]]
+            = compiler->mod->program.size;
+        }
+
+    } break;
+
     default: {
       fprintf(stderr, "Cannot compile unknown node '%s'",
               NodeTypeStr[node->type]);
@@ -328,3 +349,39 @@ int compiler_run(compiler_t* compiler, node_t* node)
 
   return 0;
 }
+
+void compiler_run_if(compiler_t* compiler, node_t* node,
+                     int* end_points, size_t* sz)
+{
+  assert(compiler);
+  assert(node);
+
+  // if
+  compiler_run(compiler, (node_t*) node->children.data[0]);
+  // if false goto next
+  int to_next = mod_push_instr(compiler->mod, OP_BRF, RZ_NO_PARAM);
+
+  // then
+  compiler_run(compiler, (node_t*) node->children.data[1]);
+  // goto end
+  int to_end = mod_push_instr(compiler->mod, OP_BR, RZ_NO_PARAM);
+  end_points[*sz] = to_end;
+  (*sz)++;
+
+  compiler->mod->program.params[to_next]
+    = compiler->mod->program.size;
+
+  if (node->children.size >= 3)
+    {
+      node_t* next = (node_t*) node->children.data[2];
+
+      if (next->type == NODE_BLOCK)
+        {
+          compiler_run(compiler, next);
+        }
+      else if (next->type == NODE_IF)
+        {
+          compiler_run_if(compiler, next, end_points, sz);
+        }
+    }
+}

lib/compiler.h

@@ -26,5 +26,7 @@ void compiler_init(compiler_t* compiler,
 void compiler_free(compiler_t* compiler);
 
 int compiler_run(compiler_t* compiler, node_t* node);
+void compiler_run_if(compiler_t* compiler, node_t* node,
+                     int* end_points, size_t* sz);
 
 #endif

lib/lexer.c

@@ -71,6 +71,9 @@ node_t* lexer_try_new_next(lexer_t* lexer)
 
   // Keywords
   // ========
+  RZ_KEYWORD("if", NODE_IF, 0);
+  RZ_KEYWORD("then", NODE_THEN, 0);
+  RZ_KEYWORD("else", NODE_ELSE, 0);
   RZ_KEYWORD("begin", NODE_BEGIN, 0);
   RZ_KEYWORD("end", NODE_END, 0);
   RZ_KEYWORD("let", NODE_LET, 0);

lib/node.h

@@ -13,7 +13,8 @@
     G(NODE_MODULO), G(NODE_POW), G(NODE_OPAR), G(NODE_CPAR),            \
     G(NODE_AND), G(NODE_OR), G(NODE_NOT),                               \
     G(NODE_LET), G(NODE_IDENT), G(NODE_ASSIGN), G(NODE_VARDECL),        \
-    G(NODE_VARSET), G(NODE_BEGIN), G(NODE_END), G(NODE_BLOCK)
+    G(NODE_VARSET), G(NODE_BEGIN), G(NODE_END), G(NODE_BLOCK),          \
+    G(NODE_SCOPE), G(NODE_IF), G(NODE_THEN), G(NODE_ELSE)
 
 RZ_ENUM_H(NodeType, NODE_TYPE);
 

lib/parser.c

@@ -64,6 +64,11 @@ node_t* parser_try_new_expr(parser_t* parser)
       return parser_try_new_varset(parser);
     }
 
+  if (type_1 == NODE_IF)
+    {
+      return parser_try_new_if(parser);
+    }
+
   if (type_1 == NODE_ASSERT)
     {
       return parser_try_new_assert(parser);
@@ -76,7 +81,7 @@ node_t* parser_try_new_expr(parser_t* parser)
 
   if (type_1 == NODE_BEGIN)
     {
-      return parser_try_new_block(parser);
+      return parser_try_new_scope(parser);
     }
 
   return parser_try_new_or(parser);
@@ -141,18 +146,69 @@ node_t* parser_try_new_block(parser_t* parser)
   node_t* block = malloc(sizeof(node_t));
   node_init(block, NODE_BLOCK, "", parser->lexer->line);
 
-  parser_skip(parser, NODE_BEGIN);
-
-  NodeType next;
-
-  while ( (next = lexer_peek(parser->lexer, 1)) != NODE_END)
+  while (1)
     {
+      NodeType next = lexer_peek(parser->lexer, 1);
+
+      if (next == NODE_END
+          || next == NODE_ELSE)
+        {
+          break;
+        }
+
       node_add_new_child(block, parser_try_new_expr(parser));
     }
 
+  return block;
+}
+
+node_t* parser_try_new_scope(parser_t* parser)
+{
+  assert(parser);
+  parser_skip(parser, NODE_BEGIN);
+  node_t* block = parser_try_new_block(parser);
   parser_skip(parser, NODE_END);
 
-  return block;
+  node_t* scope = malloc(sizeof(node_t));
+  node_init(scope, NODE_SCOPE, "", parser->lexer->line);
+  node_add_new_child(scope, block);
+
+  return scope;
+}
+
+node_t* parser_try_new_if(parser_t* parser)
+{
+  assert(parser);
+
+  node_t* node = parser_try_new_consume(parser, NODE_IF);
+  node_add_new_child(node, parser_try_new_expr(parser));
+
+  parser_skip(parser, NODE_THEN);
+  node_add_new_child(node, parser_try_new_block(parser));
+
+  int next = lexer_peek(parser->lexer, 1);
+
+  if (next == NODE_ELSE)
+    {
+      parser_skip(parser, NODE_ELSE);
+      int n = lexer_peek(parser->lexer, 1);
+
+      if (n == NODE_IF)
+        {
+          node_add_new_child(node, parser_try_new_if(parser));
+        }
+      else
+        {
+          node_add_new_child(node, parser_try_new_block(parser));
+          parser_skip(parser, NODE_END);
+        }
+    }
+  else
+    {
+      parser_skip(parser, NODE_END);
+    }
+
+  return node;
 }
 
 node_t* parser_try_new_or(parser_t* parser)

lib/parser.h

@@ -20,6 +20,8 @@ node_t* parser_try_new_assert(parser_t* parser);
 node_t* parser_try_new_vardecl(parser_t* parser);
 node_t* parser_try_new_varset(parser_t* parser);
 node_t* parser_try_new_block(parser_t* parser);
+node_t* parser_try_new_scope(parser_t* parser);
+node_t* parser_try_new_if(parser_t* parser);
 node_t* parser_try_new_or(parser_t* parser);
 node_t* parser_try_new_and(parser_t* parser);
 node_t* parser_try_new_eqne(parser_t* parser);

lib/sym.c

@@ -34,7 +34,6 @@ int sym_declare(sym_t* sym, char* name, type_t* type,
 {
   assert(sym);
   assert(name);
-  assert(type);
 
   sym_entry_t* res = sym_try_find_by_name(sym,
                                           name,

lib/type.c

@@ -23,9 +23,15 @@ int type_eq(type_t* type, type_t* rhs)
 
 size_t type_str(type_t* type, char* buffer, size_t size)
 {
-  assert(type);
   assert(buffer);
 
+  if (type)
+    {
       return snprintf(buffer, size, "%s",
                       TypeKindStr[type->kind] + strlen("TYPE_"));
+    }
+  else
+    {
+      return snprintf(buffer, size, "*unknown*");
+    }
 }

lib/tysolver.c

@@ -121,6 +121,10 @@ type_t* tysolver_try_solve_node(tysolver_t* tysolver, node_t* node)
       return ty;
     } break;
 
+    case NODE_IF: {
+      return NULL;
+    } break;
+
     default: {
       tysolver_error(tysolver, node);
     } break;

tests/acceptances/if.roza

@@ -0,0 +1,113 @@
+# SIMPLE IF
+# =========
+let count = 0
+
+if true then
+  count = 1
+end
+
+if false then
+  count = 0
+end
+
+assert count == 1
+
+# ELSE
+# ====
+count = 0
+
+if true then
+  count = count + 1
+else
+end
+
+if false then
+else
+  count = count + 1
+end
+
+assert count == 2
+
+# ELSE IF
+# =======
+count = 0
+
+if true then
+  count = 1
+else if true then
+  count = 0
+else if true then
+  count = 0
+else
+  count = 0
+end
+
+assert count == 1
+count = 0
+
+if false then
+  count = 0
+else if true then
+  count = 1
+else if true then
+  count = 0
+else
+  count = 0
+end
+
+assert count == 1
+count = 0
+
+if false then
+  count = 0
+else if false then
+  count = 0
+else if true then
+  count = 1
+else
+  count = 0
+end
+
+assert count == 1
+count = 0
+
+if false then
+  count = 0
+else if false then
+  count = 0
+else if false then
+  count = 0
+else
+  count = 1
+end
+
+assert count == 1
+
+# IF AS EXPR
+# ==========
+let a = if true then 5 else 6 end
+let b = if false then 5 else 6 end
+
+assert a == 5
+assert b == 6
+
+# IF BLOCKS
+# =========
+let c = 34
+
+if true then
+  let c = 9
+  assert c == 9
+end
+
+assert c == 34
+
+let d = "bim"
+
+if false then
+else
+  let d = "bam"
+  assert d == "bam"
+end
+
+assert d == "bim"

tests/units/lexer.c

@@ -158,7 +158,8 @@ Test(lexer, let_var) {
 }
 
 Test(lexer, blocks) {
-  test_lexer("begin end", 2,
-             "BEGIN",
-             "END");
+  test_lexer("if then else", 3,
+             "IF",
+             "THEN",
+             "ELSE");
 }

tests/units/parser.c

@@ -116,13 +116,26 @@ Test(parser, var_set) {
 }
 
 Test(parser, block) {
-  test_parser_ok("MOD(BLOCK)",
+  test_parser_ok("MOD(SCOPE(BLOCK))",
                  " begin  end ");
 
-  test_parser_ok("MOD(BLOCK(ADD(NUM[1],NUM[2])))",
+  test_parser_ok("MOD(SCOPE(BLOCK(ADD(NUM[1],NUM[2]))))",
                  " begin  1 + 2 end ");
 
-  test_parser_ok("MOD(BLOCK(VARSET(IDENT[y],BOOL[true])"
-                 ",VARSET(IDENT[z],BOOL[false])))",
+  test_parser_ok("MOD(SCOPE(BLOCK(VARSET(IDENT[y],BOOL[true])"
+                 ",VARSET(IDENT[z],BOOL[false]))))",
                  " begin y = true z = false end ");
 }
+
+Test(parser, if_then_else) {
+  test_parser_ok("MOD(IF(IDENT[x],BLOCK(IDENT[y])))",
+                 "if x then y end");
+
+  test_parser_ok("MOD(IF(IDENT[x],BLOCK(IDENT[y]),BLOCK(IDENT[z])))",
+                 "if x then y else z end");
+
+  test_parser_ok("MOD(IF(IDENT[x],"
+                 "BLOCK(IDENT[y]),"
+                 "IF(IDENT[z],BLOCK(IDENT[u]),BLOCK(IDENT[v]))))",
+                 "if x then y else if z then u else v end");
+}